Clutch assembly with fluid evacuation

ABSTRACT

A clutched device can include a differential, a clutch, and a gate. The differential can transmit torque between an input member and first and second output members. A housing can define a sump and a reservoir spaced apart from the sump. A first aperture open to the sump and reservoir can be above a static fluid level of the sump. A second aperture can couple the sump and reservoir below the static fluid level. An outer clutch plate carrier can rotate through the sump and sling fluid through the first aperture. The outer carrier can be coupled for rotation with the second output member and an inner clutch plate carrier can be coupled to a third output member. The gate can be movable between first and second positions. In the first position the gate can block the second aperture. In the second position the second aperture can be open.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/014,168 filed Feb. 3, 2016, which claims the benefit of U.S.Provisional Patent Application No. 62/114,657 filed Feb. 11, 2015. Thedisclosure of each of the above-referenced applications is incorporatedby reference as if fully set forth in detail herein.

FIELD

The present disclosure relates to a clutched device having a clutchassembly with a fluid evacuation system.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

Power transmitting components with a torque transfer device, such as adisconnecting drive module in an all-wheel drive (“AWD”) system,generally include a clutch with a plurality of friction plates and apiston for selectively engaging the friction plates. The friction platesare generally bathed in a fluid to provide lubrication and cooling ofthe plates when the clutch is engaged. When the clutch is disengaged,the plates are generally separated. When separated, excess fluid betweenthe plates and within a clutch sump through which the plates rotate, canincrease the system drag torque. It is advantageous to decrease theamount of system drag torque. Minimizing the level of fluid within theclutch sump can reduce the amount of drag torque from the clutch.However, sufficient fluid must be available during engagement of theclutch to prevent excessive temperatures and plate damage. As a result,it can be difficult to maintain the optimal amount of fluid within theclutch during both engagement and disengagement.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

The present teachings provide for a clutched device including an inputmember, a first output member, a second output member, a third outputmember, a differential, a lubricant fluid, a housing, a clutch assembly,and a gate. The input member can be configured to receive rotationalpower and rotate about a first axis. The first output member, secondoutput member, and third output member can be configured to rotate abouta second axis that is transverse to the first axis. The differential caninclude a differential case and a differential gearset. The differentialcase can be drivingly coupled to the input member. The differentialgearset can be configured to transmit rotary power between thedifferential case and the first and second output members. The housingcan have an inner wall disposed about the second axis. The housing candefine a clutch sump and a reservoir. The reservoir can be spaced apartfrom the clutch sump by the inner wall. The inner wall can define afirst aperture and a second aperture. The first aperture can be open tothe clutch sump and the reservoir. The second aperture can be spacedapart from the first aperture and can fluidly couple the clutch sump andthe reservoir. The clutch assembly can include an inner carrier, anouter carrier, a plurality of first clutch plates, and a plurality ofsecond clutch plates. The outer carrier can be configured to rotatethrough the clutch sump and sling an amount of the lubricant fluid fromthe clutch sump through the first aperture. The outer carrier can becoupled for rotation with the second output member and the inner carriercan be coupled for rotation with the third output member. The first andsecond clutch plates can be interleaved. The gate can be coupled to thehousing and can be movable between a first position and a secondposition. When the gate is in the first position, the gate can block thesecond aperture to inhibit fluid communication between the reservoir andthe clutch sump through the second aperture. When the gate is in thesecond position, the gate cannot block the second aperture so as topermit fluid communication between the reservoir and the clutch sumpthrough the second aperture. The lubricant fluid can define a staticfluid level in the clutch sump, which can be a maximum level of thelubricant fluid in the clutch sump when the inner and outer carriers arenot rotating. The first aperture can be disposed above the static fluidlevel and the second aperture can be disposed below the static fluidlevel.

The present teachings further provide for a clutched device including aninput member, a first output member, a second output member, a thirdoutput member, a differential, a lubricant fluid, a housing, a clutchassembly, and a valve. The input member can be configured to receiverotational power and rotate about a first axis. The first output member,second output member, and third output members can be configured torotate about a second axis that is transverse to the first axis. Thedifferential can include a differential case and a differential gearset.The differential case can be drivingly coupled to the input member. Thedifferential gearset can be configured to transmit rotary power betweenthe differential case and the first and second output members. Thehousing can have an inner wall disposed about the second axis. Thehousing can define a clutch sump and a reservoir. The reservoir can bespaced apart from the clutch sump by the inner wall. The inner wall candefine a first aperture that can be open to the clutch sump and thereservoir. The clutch assembly can include an inner carrier, an outercarrier, a plurality of first clutch plates, and a plurality of secondclutch plates. The outer carrier can be configured to rotate through theclutch sump and sling an amount of the lubricant fluid from the clutchsump through the first aperture. The outer carrier can be coupled forrotation with the second output member and the inner carrier can becoupled for rotation with the third output member. The first and secondclutch plates can be interleaved. The valve can include a secondaperture and a valve member. The second aperture can fluidly couple theclutch sump and the reservoir. The valve member can be movable relativeto the second aperture between a first position and a second position.When the valve member is in the first position, the valve member can beconfigured to inhibit fluid communication from the clutch sump to thereservoir through the second aperture, and when the valve member is inthe second position, the valve member can be configured to permit fluidcommunication from the reservoir to the clutch sump through the secondaperture. The lubricant fluid can define a static fluid level that canbe a maximum level of the lubricant fluid in the clutch sump when theinner and outer carriers are not rotating. The first aperture can bedisposed above the static fluid level and the second aperture can bedisposed below the static fluid level.

The present teachings further provide for a clutched device including aninput member, an output member, a housing, a clutch assembly, a firstreservoir, an evacuation device, and a pump. The housing can define aclutch sump. The clutch assembly can include a first piston chamber, afirst piston, and a plurality of interleaved clutch plates. The firstpiston can be configured to move between a first position and a secondposition. The clutch plates can be configured to rotate through theclutch sump and to transmit torque between the input member and theoutput member when the first piston is in the second position. The firstreservoir can be configured to hold a hydraulic fluid. The evacuationdevice can include a second piston chamber. The second piston can bedisposed within the second piston chamber and can be configured to movebetween a third position and a fourth position. The second piston canhave a first side and a second side. The first side of the second pistonand the second piston chamber can define a second reservoir that can bein fluid communication with the clutch sump. The second reservoir canhave a first volume when the second piston is in the third position anda second volume that is greater than the first volume when the secondpiston is in the fourth position. The second side of the second pistonand the second piston chamber can define an actuator chamber that can becoupled for fluid communication with the first piston chamber. The pumpcan be operable in a first mode wherein the pump can be configured topump the hydraulic fluid from the first reservoir to the first pistonchamber and the actuator chamber, and a second mode wherein the pump canbe configured to pump the hydraulic fluid from the first piston chamberand the actuator chamber to the first reservoir.

The present teachings further provide for a clutched device including aninput member, an output member, a housing, a lubricant fluid, a clutchassembly, and a means for controlling a volume of the lubricant fluid ina clutch sump defined by the housing. The clutch assembly can include afirst piston chamber, a first piston, and a plurality of interleavedclutch plates. The first piston can be configured to move between afirst piston position and a second piston position. The clutch platescan be configured to rotate through the clutch sump and to transmittorque between the input member and the output member when the firstpiston is in the second piston position.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a schematic view of a vehicle having a clutched deviceconstructed in accordance with the present teachings;

FIG. 2 is a sectional view of the clutched device of FIG. 1,illustrating a clutch cavity and a clutch assembly including a clutchplate carrier;

FIG. 3 is a sectional view of a portion of the clutch assembly of FIG.2, illustrating a fluid evacuation system of a first construction havinga gate in a first position;

FIG. 4 is a sectional view similar to FIG. 3, illustrating the gate in asecond position;

FIG. 5 is a sectional view of a portion of the clutch assembly of FIG.2, schematically illustrating a fluid evacuation system of a secondconstruction;

FIG. 6 is a sectional view of a portion of the clutch assembly of FIG.2, illustrating a fluid evacuation system of a third construction; and

FIG. 7 is an elevated view of the fluid evacuation system of FIG. 6.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

With reference to FIG. 1 of the drawings, an example of a vehicle havinga clutched device constructed in accordance with the teachings of thepresent disclosure is generally indicated by reference numeral 10. Thevehicle 10 can have a power train 12 and a drive line or drive train 14.The power train 12 can be conventionally constructed and can comprise apower source 16 and a transmission 18. The power source 16 can beconfigured to provide propulsive power and can comprise an internalcombustion engine and/or an electric motor, for example. Thetransmission 18 can receive propulsive power from the power source 16and can output power to the drive train 14. The transmission 18 can havea plurality of automatically or manually-selected gear ratios. The drivetrain 14 in the particular example provided is of an all-wheel drive(“AWD”) configuration, but those of skill in the art will appreciatethat the teachings of the present disclosure are applicable to otherdrive train configurations, including four-wheel drive (“4WD”)configurations, two-wheel drive (“2WD”), rear-wheel drive configurations(“RWD”), and front-wheel drive (“FWD”) configurations. The drive train14 can include a front axle assembly 20, a power take-off unit (PTU) 22,a prop shaft 24 and a rear axle assembly 26. The front axle assembly 20can be configured in any desired manner, such as a front beam axle or anindependent front drive axle. An output of the transmission 18 can becoupled to an input of the front axle assembly 20 to drive an inputmember 30 of the front axle assembly 20. The PTU 22 can have a PTU inputmember 32, which can receive rotary power from the input member 30 ofthe front axle assembly 20, and a PTU output member 34 that can transmitrotary power to the prop shaft 24. The prop shaft 24 can couple the PTUoutput member 34 to the rear axle assembly 26 such that rotary poweroutput by the PTU 22 is received by the rear axle assembly 26. The rearaxle assembly 26 can be configured in any desired manner, such as a rearbeam axle, an independent rear drive axle, or a rear drive module. Thefront axle assembly 20 and the rear axle assembly 26 can be driven on afull-time basis to drive front and rear vehicle wheels 40 and 42,respectively. The drive train 14 can include one or more clutches tointerrupt the transmission of rotary power through a part of the drivetrain 14. In the particular example provided, the drive train 14includes a first clutch 46, which can be configured to interrupt thetransmission of rotary power through the PTU 22 (e.g., decouple theinput member 30 of the front axle assembly 20 from the PTU input member32), and a second clutch 48, which can be configured to control rotationof components within the rear axle assembly 26.

In the particular example provided, the rear axle assembly 26 includes arear drive module 50 (i.e., a clutched device) that is constructed inaccordance with the teachings of the present disclosure. It will beappreciated, however, that the teachings of the present disclosure haveapplication to various other clutched devices, such as transmissions,power take-offs, torque transfer devices, transfer cases, front axleassemblies, and any other power transmitting components that have aclutch and a housing forming a clutch sump.

With reference to FIG. 2, the rear drive module 50 is illustrated inmore detail. In the example provided, the rear drive module 50 is a typeknown as a split-shaft drive module. The rear drive module 50 caninclude a housing 210, an input pinion 212, an input member 214, thesecond clutch 48, a differential assembly 216, a first output shaft 218,a second output shaft 220, and a third output shaft 222. The housing 210can define a first cavity 224 and the input pinion 212 can be a hypoidpinion having a hypoid gear 226, an input pinion shaft 228, and an inputpinion flange 238. The input pinion flange 238 can be drivingly coupledto the prop shaft 24 (FIG. 1). The hypoid gear 226 can be disposedwithin the first cavity 224. The input pinion shaft 228 can be supportedfor rotation in the housing 210 along a first axis 230 by a head bearing232 proximate to the hypoid gear 226 and a tail bearing 234 distal tothe hypoid gear 226 and proximate to the input pinion flange 238 andprop shaft 24. The input member 214 can be a ring gear having a gearface 236. The input member 214 can be supported for rotation in thehousing 210 about a second axis 242 by a bearing 244. The second axis242 can be generally transverse or perpendicular to the first axis 230.The gear face 236 can be meshingly engaged with the hypoid gear 226.

The differential assembly 216 can include a differential case 250 and adifferential gearset 252. The differential case 250 can be configuredfor rotation about the second axis 242. The differential case 250 can bedrivingly coupled to the input member 214. The differential case 250 canbe supported within the housing 210 by a bearing 254 and can be coupledto the input member 214 for common rotation about the second axis 242.The differential gearset 252 can be configured to transmit rotary powerbetween the differential case 250 and the first and second output shafts218, 220. In the example provided, the differential gearset 252 includesa pair of side gears 256 (only one of which is shown) and a pair ofoutput gears 258 disposed within the differential case 250. The sidegears 256 can be coupled for rotation with the differential case 250about the second axis 242 and coupled for rotation relative to thedifferential case 250 about a cross pin 260. The cross pin 260 can begenerally perpendicular to the second axis 242. The output gears 258 canbe meshingly engaged with the side gears 256 and configured to rotateabout the second axis 242. The first output shaft 218 can be drivinglycoupled to one of the output gears 258 and can be coupled for commonrotation therewith. The first output shaft 218 can be drivingly coupledto one of the rear wheels 42 (FIG. 1). The second output shaft 220 canbe drivingly coupled to the other of the output gears 258 and can becoupled for common rotation therewith. The third output shaft 222 can bedrivingly coupled to the other one of the rear wheels 42 (FIG. 1).

The second clutch 48 can be selectively operated to transmit rotarypower from the second output shaft 220 to the third output shaft 222. Inthe particular example provided, the second clutch 48 is a frictionclutch that is mounted co-axially with the input member 214 and thedifferential assembly 216 about the second axis 242. The second clutch48 can include a clutch housing 310, an outer clutch plate carrier 312,an inner clutch plate carrier 314, a plurality of first clutch plates316, a plurality of second clutch plates 318, a first piston 330, anapply plate 332, a pump 334, a pump motor 336, a first reservoir 338,and a fluid evacuation system 340 (FIGS. 3 and 4). The clutch housing310 can be integrally formed with or partially formed by the housing 210of the rear drive module 50 or can be separately formed and mounted tothe housing 210. The clutch housing 310 can include a shell 350 and anend cap 352. The shell 350 can have an inner wall 354 that can begenerally cylindrical in shape. The inner wall 354 and the end cap 352can define a second cavity 356. The shell 350 and end cap 352 can alsodefine a first piston chamber 358. The shell 350 can separate the firstcavity 224 from the second cavity 356.

The outer and inner clutch plate carriers 312, 314 and the first andsecond clutch plates 316, 318 can be received in the second cavity 356.One of the outer and inner clutch plate carriers 312, 314 can benon-rotatably coupled to the third output shaft 222 and the plurality offirst clutch plates 316. The other of the outer and inner clutch platecarriers 312, 314 can be non-rotatably coupled to the second outputshaft 220 and the plurality of second clutch plates 318. In theparticular example provided, the outer clutch plate carrier 312 isnon-rotatably coupled to the second output shaft 220 and the pluralityof first clutch plates 316, while the inner clutch plate carrier 314 isnon-rotatably coupled to the third output shaft 222 and the plurality ofsecond clutch plates 318. The inner clutch plate carrier 314 and thethird output shaft 222 can be supported within the clutch housing 310for rotation relative thereto by a bearing 362. In the example providedthe bearing 362 is located radially between the inner clutch platecarrier 314 and the end cap 352, though other configurations can beused. In the example provided, the inner clutch plate carrier 314includes a set of interior splines 364 that are meshingly engaged with aset of exterior splines 366 formed on the third output shaft 222 tonon-rotatably couple the third output shaft 222 and the inner clutchplate carrier 314. The second clutch plates 318 can be interleaved withthe first clutch plates 316 radially between the outer and inner clutchplate carriers 312, 314.

The first piston 330 can be received in the first piston chamber 358 andconfigured to translate along the second axis 242. The first piston 330can be configured to move within the first piston chamber 358 between anextended position and a retracted position relative to the plurality offirst and second clutch plates 316, 318. The pump 334 can be mounted tothe housing 210 or the clutch housing 310 proximate to the pinion shaft228 in a space generally nestled between the housing 210 and the clutchhousing 310. The pump motor 336 can be a 2-way servo motor capable ofrunning in forward and reverse and can be drivingly coupled to the pump334 to selectively operate the pump 334.

The pump 334 can be fluidly coupled to the first reservoir 338 by afirst pump conduit 370 and fluidly coupled to the first piston chamber358 by a second pump conduit 372. In the example provided, the secondpump conduit 372 is defined by the clutch housing 310. Whileschematically shown in FIG. 2 the first pump conduit 370 can also bedefined by the clutch housing 310 and/or the housing 210. The firstreservoir 338 can be configured to hold a hydraulic fluid. The pump 334can be operated in a first mode to pump the hydraulic fluid in a firstdirection to supply the hydraulic fluid from the first reservoir 338 tothe first piston chamber 358 to move the first piston 330 from theretracted position to the extended position. The pump 334 can beoperated in a second mode to pump hydraulic fluid in a second directionto selectively remove hydraulic fluid from the first piston chamber 358to the first reservoir 338 to move the first piston 330 from theextended position to the retracted position. The first reservoir 338 canbe mounted to the housing 210 or the clutch housing 310. Alternatively,the first reservoir 338 can be integrally formed with the housing 210 orthe clutch housing 310. The first reservoir 338 can also include a vent(not shown) that can vent gasses to the atmosphere or another part ofthe rear drive module 50.

The apply plate 332 can be disposed in the second cavity 356 between thefirst piston 330 and the plurality of first and second clutch plates316, 318. The first piston 330 can be configured to translate the applyplate 332 along the second axis 242 to selectively engage the first andsecond clutch plates 316, 318 to compress the first and second clutchplates 316, 318 against one another so that the second clutch 48 cantransmit rotary power between the second and third output shafts 220,222. It will be appreciated that the second clutch 48 can be configuredto not transmit rotary power between the second and third output shafts220, 222 when the first piston 330 is in the retracted position. Thesecond clutch 48 can also be configured to transmit various levels oftorque by varying the position of the first piston 330 relative to thefirst and second clutch plates 316, 318.

With additional reference to FIGS. 3 and 4, a lower portion of thesecond cavity 356 can define a clutch sump 410 wherein a lubricant fluidcan collect up to a static fluid level 414. The static fluid level 414can be the maximum height of the lubricant fluid when the vehicle 10 ison a level surface, the outer and inner clutch plate carriers 312, 314are not rotating, and all or substantially all of the lubricant fluid isdisposed within the clutch sump 410. The fluid evacuation system 340 caninclude a second reservoir 418, a gate 422, and a hinge 426. The clutchhousing 310 can define the second reservoir 418. The inner wall 354 cangenerally separate the second reservoir 418 from the second cavity 356and the clutch sump 414. The inner wall 354 can define a first aperture430, and a second aperture 434. A portion 438 of the inner wall 354 canextend radially outward from the surrounding inner wall 354 to define arecess 442 that can be open to the clutch sump 410 and located below thestatic fluid level 414. The first and second apertures 430, 434 canpermit fluid communication between the second cavity 356 and the secondreservoir 418. The first aperture 430 can be above the static fluidlevel 414 and open to the second cavity 356 and the second reservoir418. The second aperture can be below the static fluid level 414 and canfluidly couple the second reservoir 418 and the recess 442.

The gate 422 can be coupled to the clutch housing 310 by the hinge 426.The hinge 426 can be located within the recess 442. The gate 422 canpivot about the hinge 426 between an open position (FIG. 3) and a closedposition (FIG. 4). When in the open position, the gate 422 is spacedaway from the second aperture 434 and fluid communication between thesecond reservoir 418 and the second cavity 356 is permitted through thesecond aperture 434. When in the closed position, the gate 422 coversthe second aperture 434 to inhibit fluid communication between thesecond reservoir 418 and the second cavity 356 through the secondaperture 434.

In operation, the first output shaft 218 and the third output shaft 222can be coupled to rotate in the same rotational direction as thevehicle's wheel 42 (FIG. 1) to which each is drivingly coupled. When thefirst and second clutch plates 316, 318 are engaged to transmit torquebetween the second and third output shafts 220, 222, the outer clutchplate carrier 312 can rotate in the same rotational direction as thevehicle wheel 42 to which the third output shaft 222 is drivinglycoupled. When the first and second clutch plates 316, 318 are engaged,the outer clutch plate carrier 312 can rotate in a first rotationaldirection 450 (FIG. 3). When the first and second clutch plates 316, 318are disengaged, the differential gearset 252 causes the second outputshaft 220, and thus the outer clutch plate carrier 312 to rotate in theopposite rotational direction as the vehicle wheel 42 to which the firstand third output shafts 218, 222 are coupled. Thus, when the first andsecond clutch plates 316, 318 are disengaged, the outer clutch platecarrier 312 can rotate in a second rotational direction 452 (FIG. 4)that is opposite the first rotational direction 450.

When the outer clutch plate carrier 312 rotates in the first rotationaldirection 450 (FIG. 3), the outer clutch plate carrier 312 can act onthe lubrication fluid in the clutch sump 410 to churn and pull thelubrication fluid in the first direction 450. Some of the lubricationfluid in the clutch sump 410 can cling to the outer clutch plate carrier312 and can be slung from the outer clutch plate carrier 312 toward theinner wall 354 above the static fluid level 414. Some of the fluid slungonto the inner wall 354 can run down the inner wall 354 and through thefirst aperture 430, into the second reservoir 418. Some of thelubrication fluid can also be slung from the outer clutch plate carrier312 directly through the first aperture 430 and into the secondreservoir 418. The first aperture 430 can be located along the innerwall 354 such that when the outer clutch plate carrier 312 rotates inthe first direction 450, fluid slung directly through the first aperture430 is slung in a generally downward direction to impinge on fluidalready collected in the second reservoir 418. As the lubricant fluidcollects in the second reservoir 418 above the second aperture 434, thelocal pressure at the second aperture 434 acting on the gate 422 canincrease due to the weight of the fluid and the additional fluid beingslung into the second reservoir 418.

The churning of the lubrication fluid in the first direction 450 canalso create an area of low pressure or suction in the recess 442, anddraw fluid from the recess 442. The pressure differential between thesecond reservoir 418 at the second aperture 434 and the clutch sump 410at the recess 442 can cause the gate 422 to move from the closedposition to the open position and draw fluid from the second reservoir418, through the second aperture 434 and back into the clutch sump 410.The flow of lubricant fluid through the second aperture 434 and into theclutch sump 410 can prevent the second reservoir 418 from becomingfilled with lubricant fluid and can ensure adequate lubricant fluidremains in the clutch sump 410 while the clutch plates 316, 318 areengaged.

When the outer clutch plate carrier 312 rotates in the second rotationaldirection 452 (FIG. 4), the outer clutch plate carrier 312 can act onthe lubrication fluid in the clutch sump 410 to churn and pull the fluidin the second direction 452. Some of the fluid in the clutch sump 410can cling to the outer clutch plate carrier 312 and can be slung fromthe outer clutch plate carrier 312 toward the inner wall 354 above thestatic fluid level 414. Some of the fluid slung onto the inner wall 354can run down the inner wall 354 and through the first aperture 430, intothe second reservoir 418. Some of the fluid can also be slung from theouter clutch plate carrier 312 directly through the first aperture 430and into the second reservoir 418. The first aperture 430 can be locatedsuch that when the outer clutch plate carrier 312 rotates in the seconddirection 452, the fluid slung through the first aperture 430 can begenerally slung upwards through the first aperture 430 and into thesecond reservoir 418.

The churning of the lubrication fluid in the second direction 452 canalso push fluid in the clutch sump 410 toward the recess 442 to createan area of higher pressure in the recess 442 and/or impinge on the gate422. The pressure differential between the second reservoir 418 at thesecond aperture 434 and the clutch sump 410 at the recess 442 can causethe gate 422 to move from the opened position to the closed position toinhibit fluid from exiting the second reservoir 418 through the secondaperture 434. The flow of lubricant fluid through the first aperture 430and into the second reservoir 418, while the second aperture 434 remainsclosed, can cause the second reservoir 418 to become filled withlubricant fluid and reduce the amount of lubricant fluid that remains inthe clutch sump 410 while the clutch plates 316, 318 are disengaged.

Thus, the gate 422 can be moved to the open position when the pressuredifferential is greater than a predetermined pressure differential andmoved to the closed position when the pressure differential is less thanthe predetermined pressure differential. Thus, the gate 422, hinge 426,and second aperture 434 can act as a one-way valve with second aperture434 acting as a valve body and the gate 422 operating as a valve memberconfigured to open and close the valve body to permit flow of fluid fromthe second reservoir 418 to the clutch sump 410, while inhibiting flowfrom the clutch sump 410 to the second reservoir 418. It is understoodthat other types of one-way valves can be used. While not specificallyshown, a biasing member such as a spring could be used to bias the gate422 toward either of the open or closed positions such that the gate 422is moved to the open or closed position when the pressure differentialis greater than a predetermined pressure differential based on thebiasing force of the biasing member. Thus, the fluid evacuation system340 can be a means for controlling the volume of hydraulic fluid withinthe clutch sump 410.

With reference to FIG. 5, a fluid evacuation system of a secondconstruction is indicated by reference numeral 510. The fluid evacuationsystem 510 can be used with the second clutch 48 described in detailabove. Those of skill in the art will appreciate that the fluidevacuation system 510 is applicable to other similar drivelinecomponents or clutches. The fluid evacuation system 510 can include athird pump conduit 514, a second piston chamber 518, a second piston522, and a fluid level conduit 526. While schematically illustrated, thesecond piston chamber 518 can be wholly or partially defined by thehousing 210 or the clutch housing 310, or can be a body separate fromthe housing 210 and clutch housing 310.

The second piston 522 can have a first piston side 530 and a secondpiston side 534. The first piston side 530 can be disposed within thesecond piston chamber 518 to partially define a variable volume fluidcontainer or second reservoir 538 and the second piston side 534 can bedisposed within the second piston chamber 518 to partially define anactuator chamber 542. The second reservoir 538 can be coupled for fluidcommunication with the clutch sump 410 by the fluid level conduit 526.The fluid level conduit 526 can be wholly or partially defined by thehousing 210 or clutch housing 310, or can be separately coupled thereto.The actuator chamber 542 can be coupled for fluid communication with thepump 334 by the third pump conduit 514. The third pump conduit 514 canbe wholly or partially defined by the housing 210 or clutch housing 310,or can be separately coupled thereto.

The second piston 522 can be movable within the second piston chamber518 between a first position 546 and a second position 550. The firstand second piston sides 530, 534 can be fixedly coupled for commontranslation. The volume of the second reservoir 538 can be larger whenthe second piston 522 is in the first position 546 than when it is inthe second position 550. In the example provided, the second piston side534 has a smaller diameter than the first piston side 530 and the secondpiston chamber 518 is vented by a vent 554 located between the first andsecond piston sides 530, 534 to prevent pressure buildup behind thefirst piston side 530 and permit the second piston 522 to move betweenthe first and second positions 546, 550. The second piston side 534 canhave a piston displacement that is significantly smaller than the pistondisplacement of the first piston side 530. The piston displacement ofthe second piston side 534 can also be significantly smaller than thepiston displacement of the first piston 330. The second pump conduit 372can be coupled for fluid communication with the third pump conduit 514.

In operation, when the pump 334 is operated in the first mode to pumpthe hydraulic fluid from the first reservoir 338 to the first pistonchamber 358, some of the fluid can also be pumped through the third pumpconduit 514 to the actuator chamber 542. Fluid pumped into the actuatorchamber 542 exerts pressure on the second piston side 534 to move thesecond piston 522 from the first position 546 toward the second position550. As the second piston 522 moves from the first position 546 to thesecond position 550, the volume of the second reservoir 538 decreases,causing lubricant fluid within the second reservoir 538 to flow from thesecond reservoir 538 into the clutch sump 410 through the fluid levelconduit 526. Thus, when the pump 334 is operated in the first mode, thefirst and second clutch plates 316, 318 are moved into contact with oneanother to transmit torque and lubrication fluid is introduced into theclutch sump 410 to lubricate the first and second clutch plates 316, 318while they are brought into contact.

When the pump 334 is operated in the second mode to pump the hydraulicfluid from the first piston chamber 358 to the first reservoir 338, thepump 334 also pumps hydraulic fluid from the actuator chamber 542 to thefirst reservoir 338. Removal of the hydraulic fluid from the actuatorchamber 542 causes the second piston 522 to move from the secondposition 550 toward the first position 546. As the second piston 522moves from the second position 550 to the first position 546, the volumeof the second reservoir 538 increases, drawing lubricant fluid from theclutch sump 410 through the fluid level conduit 526 and into the secondreservoir 538. Thus, when the pump 334 is operated in the second mode,the first and second clutch plates 316, 318 are moved apart from oneanother and lubricant fluid is removed from the clutch sump 410 toreduce drag caused by the rotation of the outer clutch plate carrier 312and the first and second clutch plates 316, 318 through the lubricantfluid in the clutch sump 410. Thus, the fluid evacuation system 510 canbe a means for controlling the volume of hydraulic fluid within theclutch sump 410.

With reference to FIGS. 6 and 7, a fluid evacuation system of a thirdconstruction is indicated by reference numeral 610. The fluid evacuationsystem 610 can be used with the second clutch 48 described in detailabove. Those of skill in the art will appreciate that the fluidevacuation system 610 is applicable to other similar drivelinecomponents or clutches. The fluid evacuation system 610 can include asecond piston chamber 614, second piston 618, a diaphragm 622, a thirdpump conduit 626, a stop member 630, and a vent conduit 634. The secondpiston chamber 614 can have a first portion 638 and a second portion642. The first portion 638 can have a side wall 646 and a back wall 650.In the example provided, the first portion 638 is a recess defined bythe clutch housing 310 and open to the bottom of the clutch sump 410.The second portion 642 can be formed in the back wall 650 of the firstportion 638 and can be open to the first portion 638. The second portion642 can be a diameter that is less than the diameter of the firstportion 638.

The second piston 618 can have a first piston side 654 and a secondpiston side 658. The first piston side 654 can be disposed within thefirst portion 638. The second piston side 658 can be disposed within thesecond portion 642. The first and second piston sides 654, 658 can befixedly coupled for common translation along an axis 660 between a firstposition 670 and a second position 672. The first piston side 654 can bea diameter that is less than the diameter of the side wall 646 of thefirst portion 638 and the diaphragm 622 can extend between the firstpiston side 654 and the side wall 646 to define a second reservoir 680.The diaphragm 622 can be fixedly coupled to the side wall 646 and thefirst piston side 654. The diaphragm 622 can be a flexible or resilientmaterial to permit the first piston side 654 to move along the axis 660between the first position 670 and the second position 672 to increaseor decrease the volume of the second reservoir 680. The volume of thesecond reservoir 680 can be larger when the second piston 618 is in thefirst position 670 than when in the second position 672.

The vent conduit 634 can be coupled for fluid communication with thearea of the first portion 638 that is separated from the secondreservoir 680 by the first piston side 654 and the diaphragm 622. Thevent conduit 634 can be open to the atmosphere or another area (notspecifically shown) of the rear drive module 50 to prevent pressurebuildup behind the first piston side 654 and permit the second piston618 to move between the first and second positions 670, 672. The stopmember 630 can be configured to limit the axial travel of the secondpiston 618. In the example provided, the stop member 630 is a strip orplate of rigid material mounted to the clutch housing 310 across the topof the first portion 638. The second piston 618 can move axially towardthe outer clutch plate carrier 312 until contacting the stop member 630at the second position 672. It is understood that the stop member 630can be constructed in other ways to limit axial travel of the secondpiston 618.

The second piston side 658 and the second portion 642 can define anactuator chamber 684. The second piston side 658 can be a diameter thatis smaller than the diameter of the first piston side 654 to have asmaller piston displacement than the first piston side 654. The pistondisplacement of the second piston side 658 can be significantly smallerthan a piston displacement of the first piston 330. A seal, such as ano-ring 688 for example, can seal the second piston side 658 within thesecond portion 642. The third pump conduit 626 can fluidly couple theactuator chamber 684 with the pump 334 and the second pump conduit 372.

In operation, when the pump 334 is operated in the first mode to pumpthe hydraulic fluid from the first reservoir 338 to the first pistonchamber 358 (FIG. 2), some of the hydraulic fluid can also be pumpedthrough the third pump conduit 626 to the actuator chamber 684. Fluidpumped into the actuator chamber 684 exerts pressure on the secondpiston side 658 to move the second piston 618 from the first position670 toward the second position 672. As the second piston 618 moves fromthe first position 670 to the second position 672, the volume of thesecond reservoir 680 decreases, causing lubricant fluid within thesecond reservoir 680 to flow from the second reservoir 680 into theclutch sump 410. Thus, when the pump 334 is operated in the first mode,the first and second clutch plates 316, 318 are moved into contact withone another to transmit torque and lubrication fluid is introduced intothe clutch sump 410 to lubricate the first and second clutch plates 316,318 while they are brought into contact.

When the pump 334 is operated in the second mode to pump the hydraulicfluid from the first piston chamber 358 to the first reservoir 338, thepump 334 also pumps hydraulic fluid from the actuator chamber 684 to thefirst reservoir 338. Removal of the hydraulic fluid from the actuatorchamber 684 causes the second piston 618 to move from the secondposition 672 toward the first position 670. As the second piston 618moves from the second position 672 to the first position 670, the volumeof the second reservoir 680 increases, drawing lubricant fluid from theclutch sump 410 and into the second reservoir 680. Thus, when the pump334 is operated in the second mode, the first and second clutch plates316, 318 are moved apart from one another and lubricant fluid is removedfrom the clutch sump 410 to reduce drag caused by the rotation of theouter clutch plate carrier 312 and first and second clutch plates 316,318 through the lubricant fluid in the clutch sump 410. Thus, the fluidevacuation system 610 can be a means for controlling the volume ofhydraulic fluid within the clutch sump 410

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

Example embodiments are provided so that this disclosure will bethorough, and will fully convey the scope to those who are skilled inthe art. Numerous specific details are set forth such as examples ofspecific components, devices, and methods, to provide a thoroughunderstanding of embodiments of the present disclosure. It will beapparent to those skilled in the art that specific details need not beemployed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “a,” “an,” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The terms “comprises,” “comprising,” “including,” and“having,” are inclusive and therefore specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. The method steps, processes, and operations described hereinare not to be construed as necessarily requiring their performance inthe particular order discussed or illustrated, unless specificallyidentified as an order of performance. It is also to be understood thatadditional or alternative steps may be employed.

When an element or layer is referred to as being “on,” “engaged to,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, engaged, connected or coupled to the other element orlayer, or intervening elements or layers may be present. In contrast,when an element is referred to as being “directly on,” “directly engagedto,” “directly connected to,” or “directly coupled to” another elementor layer, there may be no intervening elements or layers present. Otherwords used to describe the relationship between elements should beinterpreted in a like fashion (e.g., “between” versus “directlybetween,” “adjacent” versus “directly adjacent,” etc.). As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items.

Although the terms first, second, third, etc. may be used herein todescribe various elements, components, regions, layers and/or sections,these elements, components, regions, layers and/or sections should notbe limited by these terms. These terms may be only used to distinguishone element, component, region, layer or section from another region,layer or section. Terms such as “first,” “second,” and other numericalterms when used herein do not imply a sequence or order unless clearlyindicated by the context. Thus, a first element, component, region,layer or section discussed below could be termed a second element,component, region, layer or section without departing from the teachingsof the example embodiments.

Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,”“lower,” “above,” “upper,” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. Spatiallyrelative terms may be intended to encompass different orientations ofthe device in use or operation in addition to the orientation depictedin the figures. For example, if the device in the figures is turnedover, elements described as “below” or “beneath” other elements orfeatures would then be oriented “above” the other elements or features.Thus, the example term “below” can encompass both an orientation ofabove and below. The device may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein interpreted accordingly.

What is claimed is:
 1. A clutched device comprising: an input memberconfigured to receive rotational power and rotate about a first axis; afirst output member, a second output member, and a third output member,the first, second, and third output members configured to rotate about asecond axis that is transverse to the first axis; a differentialincluding a differential case and a differential gearset, thedifferential case being drivingly coupled to the input member, thedifferential gearset being configured to transmit rotary power betweenthe differential case and the first and second output members; alubricant fluid; a housing having an inner wall disposed about thesecond axis, the housing defining a clutch sump and a reservoir, thelubricant fluid being received in the clutch sump and the reservoirbeing spaced apart from the clutch sump by the inner wall, the innerwall defining a first aperture and a second aperture the first aperturebeing open to the clutch sump and the reservoir, the second aperturespaced apart from the first aperture and fluidly coupling the clutchsump and the reservoir; a clutch assembly including an inner carrier, anouter carrier, a plurality of first clutch plates, and a plurality ofsecond clutch plates, the outer carrier being configured to rotatethrough the clutch sump and sling an amount of the lubricant fluid fromthe clutch sump through the first aperture, the outer carrier beingcoupled for rotation with the second output member, the inner carrierbeing coupled for rotation with the third output member, the first andsecond clutch plates being interleaved; and a gate coupled to thehousing and movable between a first position and a second position,wherein when the gate is in the first position, the gate blocks thesecond aperture to inhibit fluid communication between the reservoir andthe clutch sump through the second aperture, and wherein when the gateis in the second position, the gate does not block the second apertureso as to permit fluid communication between the reservoir and the clutchsump through the second aperture; wherein the lubricant fluid defines astatic fluid level in the clutch sump, the static fluid level being amaximum level of the lubricant fluid in the clutch sump when the innerand outer carriers are not rotating, the first aperture being disposedabove the static fluid level and the second aperture being disposedbelow the static fluid level.
 2. The clutched device of claim 1, whereinthe gate is configured to move from the first position to the secondposition when a pressure differential between the reservoir and theclutch sump is greater than a predetermined pressure differential. 3.The clutched device of claim 1, wherein the inner wall defines a recessbelow the static fluid level and open to the clutch sump, wherein thesecond aperture extends between the reservoir and the recess.
 4. Theclutched device of claim 3, wherein the gate is disposed within therecess.
 5. The clutched device of claim 1, wherein the gate is coupledto the housing by a hinge and configured to pivot about the hingebetween the first and second positions.
 6. The clutched device of claim1, wherein rotation of the outer carrier in a first rotational directionis configured to position the gate in the first position, and rotationof the outer carrier in a second rotational direction is configured toposition the gate in the second position.
 7. A clutched devicecomprising: an input member configured to receive rotational power androtate about a first axis; a first output member, a second outputmember, and a third output member, the first, second, and third outputmembers configured to rotate about a second axis that is transverse tothe first axis; a differential including a differential case and adifferential gearset, the differential case being drivingly coupled tothe input member, the differential gearset being configured to transmitrotary power between the differential case and the first and secondoutput members; a lubricant fluid; a housing having an inner walldisposed about the second axis, the housing defining a clutch sump and areservoir, the lubricant fluid being received in the clutch sump and thereservoir being spaced apart from the clutch sump by the inner wall, theinner wall defining a first aperture being open to the clutch sump andthe reservoir; a clutch assembly including an inner carrier, an outercarrier, a plurality of first clutch plates, and a plurality of secondclutch plates, the outer carrier being configured to rotate through theclutch sump and sling an amount of the lubricant fluid from the clutchsump through the first aperture, the outer carrier being coupled forrotation with the second output member and the inner carrier beingcoupled for rotation with the third output member, the first and secondclutch plates being interleaved; and a valve including a second apertureand a valve member, the second aperture fluidly coupling the clutch sumpand the reservoir, the valve member being movable relative to the secondaperture between a first position and a second position, wherein whenthe valve member is in the first position, the valve member isconfigured to inhibit fluid communication from the clutch sump to thereservoir through the second aperture, and wherein when the valve memberis in the second position, the valve member is configured to permitfluid communication from the reservoir to the clutch sump through thesecond aperture; wherein the lubricant fluid defines a static fluidlevel in the clutch sump, the static fluid level being a maximum levelof the lubricant fluid in the clutch sump when the inner and outercarriers are not rotating, the first aperture being disposed above thestatic fluid level and the second aperture being disposed below thestatic fluid level.
 8. The clutched device of claim 7, wherein the valvemember is configured to move from the first position to the secondposition when a pressure differential between the reservoir and theclutch sump is greater than a predetermined pressure differential. 9.The clutched device of claim 7, wherein the inner wall defines a recessbelow the static fluid level and open to the clutch sump, wherein thesecond aperture extends between the reservoir and the recess.
 10. Theclutched device of claim 9, wherein the valve member is disposed withinthe recess.
 11. The clutched device of claim 7, wherein the valve memberis coupled to the housing by a hinge and configured to pivot about thehinge between the first and second positions.
 12. The clutched device ofclaim 7, wherein rotation of the outer carrier in a first rotationaldirection is configured to position the valve member in the firstposition, and rotation of the outer carrier in a second rotationaldirection is configured to position the valve member in the secondposition.
 13. A disconnecting axle assembly comprising: an axle housingdefining a differential cavity and a clutch cavity, the clutch cavityhaving a clutch sump; a differential assembly received in thedifferential cavity, the differential assembly having a differentialoutput member; a clutch assembly received in the clutch cavity, theclutch assembly having a clutch input member, which is rotatably coupledto the differential output member, a clutch output member, a cylinderassembly and a clutch pack, the cylinder assembly having a first pistonchamber with a first piston that is configured to move between a firstposition and a second position, the clutch pack having a plurality ofinterleaved clutch plates that are configured to rotate through theclutch sump and to transmit torque between the clutch input member andthe clutch output member when the first piston is in the secondposition; a first reservoir configured to hold a hydraulic fluid; anevacuation device including a second piston chamber and a second pistondisposed within the second piston chamber and configured to move betweena third position and a fourth position, the second piston having a firstside and a second side, the first side of the second piston and thesecond piston chamber defining a second reservoir, the second reservoirbeing in fluid communication with the clutch sump and having a firstvolume when the second piston is in the third position and a secondvolume that is greater than the first volume when the second piston isin the fourth position, and the second side of the second piston and thesecond piston chamber defining an actuator chamber that is coupled forfluid communication with the first piston chamber; and a pump operablein a first mode wherein the pump is configured to pump the hydraulicfluid from the first reservoir to the first piston chamber and theactuator chamber, and a second mode wherein the pump is configured topump the hydraulic fluid from the first piston chamber and the actuatorchamber to the first reservoir.